Print core cleaning During a print

[Youngbosambo 1]

Hi, Just wondering if there is a way to clean a print core during the middle of a print. I’ve tried reloading, however once the material loads, it fails to extrude during the load process. When I try selecting print core clean it is greyed out (unselectable).
Do I have to abort and start the job again, or is there a way to clean print core without aborting.

Thanks

[Youngbosambo 1]

Apologies, should mention, I have an Ultimaker S3

[gr5 2,172]

I don't think you can run the "cold pull" feature but you can do it manually - for a cold pull you set the temperature to typical printing temperature, remove the bowden, push down on the filament into the hot core and then lower the temperature to the "cold" temp.  Maintain downward pressure until it gets to the cold temp.  Once the temp reaches the cold temp you pull up quite hard and if you get it just right it takes quite a bit of force - maybe 5 pounds force (so do it with the print head in a corner so you don't bend the rods) and then if you are lucky the tip of the filament is shaped like the inside of the nozzle including the tip.  And any clogs come out as well.

 

Then cut off the end of the filament and repeat (if you want).  If the filament came out too easily then try a lower cold temp the next time.  If it won't come out at all, raise the temp by 5C and keep trying.

 

Typical "cold" temps:

PLA  95C

Nylon 120C

 

But for me I mostly only get clogs on PVA.  All other materials - I haven't had a clog that needed a cold pull in over a year (that's with 5 active printers.  not non-stop.  Not every day.  But I typically have 3 printers going simultaneously for at least a few hours every week)

 

 

Anyway, my point is you can play with the temperature while the printer is paused (I think?  Pretty sure.) so that's all you need to be able to do in order to change cores, change filament, clean a core, etc.

[Youngbosambo 1]

Thanks for the reply, couldn’t access any changes to print core temps while job was in progress. Had to abort and start again… 19hours😥. Oh well. 🤷‍♂️

[gr5 2,172]

ug. 😞  There are ways to continue a print but you have to keep the heated bed hot in the meantime and you have to disable active leveling and there are all kinds of tricks you need to learn.  I would go for it but I recommend most people just start over.

[Youngbosambo 1]

Cool, thanks for your time. 
But guess what, I worked it out.

As you can can change material during a print, ie if you run out of material.

As I have been using a generic wood base material recently it has jammed a couple of times, otherwise like you the only other material I’ve similar problems to is the natural PVA.

Anyway what I worked out is if you select change material, then go through the process of unloading, reloading etc. Once the material is unloaded you can remove the the Bowden tube, then

”Pretend” to load new material.

When the printer is waiting for you to confirm ‘extrusion is flowing freely’ you can get some PLA material and proceed with a hot pull.

What I found though was I had to repeat this procedure about 3 times before I could get the material flowing freely, (as the system times out after a couple of minutes), then whoa behold material flowed freely, i reattached the Bowden tube, reloaded the material properly and continued print as normal. Seemed to work like a charm. 

Just a note when I was on the ‘confirm extrusion is flowing freely’ step, I would put the PLA material in for a few seconds, pull it out cut the dirty tip off, reinsert and repeat constantly using pliers and apply slight pressure. 
 

Hope this can help any others out experiencing the same problem. 

 

[GoguyT3d 8]

On 6/28/2022 at 7:22 PM, gr5 said:

I don't think you can run the "cold pull" feature but you can do it manually - for a cold pull you set the temperature to typical printing temperature, remove the bowden, push down on the filament into the hot core and then lower the temperature to the "cold" temp.  Maintain downward pressure until it gets to the cold temp.  Once the temp reaches the cold temp you pull up quite hard and if you get it just right it takes quite a bit of force - maybe 5 pounds force (so do it with the print head in a corner so you don't bend the rods) and then if you are lucky the tip of the filament is shaped like the inside of the nozzle including the tip.  And any clogs come out as well.

 

Then cut off the end of the filament and repeat (if you want).  If the filament came out too easily then try a lower cold temp the next time.  If it won't come out at all, raise the temp by 5C and keep trying.

 

Typical "cold" temps:

PLA  95C

Nylon 120C

 

But for me I mostly only get clogs on PVA.  All other materials - I haven't had a clog that needed a cold pull in over a year (that's with 5 active printers.  not non-stop.  Not every day.  But I typically have 3 printers going simultaneously for at least a few hours every week)

 

 

Anyway, my point is you can play with the temperature while the printer is paused (I think?  Pretty sure.) so that's all you need to be able to do in order to change cores, change filament, clean a core, etc.

What I am trying to figure out is: what the "Cold temp" is that ultimaker s3 uses when using cleaning filament (clear PC) because I have great success cleaning my ultimaker but can't figure the temp on my ender v6

[gr5 2,172]

I don't know but if the temp is too low you can't get the filament out of the nozzle.  And if the temp is too high it comes out too easily.  So just start experimenting.  When you get close you crank the heat and pull hard at the same time and remember what temp it was at when you finally get it out.  Then you will know it's somewhere near that temp (a bit lower).

 

Keep experimenting.  By the 3rd time you try it you'll probably know the proper temp.

[GoguyT3d 8]

I'm currently at My 20th try, anyone have simple access to the numbers listed in the firmware?

[gr5 2,172]

20th try?  How hard can it be.  If it's too cold you can't pull it out.  If it's too hot it comes out too easy.  Pull very hard.  Harder than enough force to lift the printer off the table.

[GoguyT3d 8]

Regardless that the third try was my pliers stabbing 2 gaping holes in my left palm, I'd simply like to know the Temps not condescending comments

[mrender 25]

About 90 degrees Celsius I think, don't think GR5 was trying to be condescending:)

[gr5 2,172]

This is for polycarbonate, right?  PLA is around 90-100C but I don't know about PC.  I assume PC is much hotter but I don't know.

[mrender 25]

Yes the cold pulls work well at that temp for both.  I assume it is more about keeping the nozzle heat expanded enough to not grip the filament solid!?

[gr5 2,172]

The temp is chosen so that it is not too hot and not too cold.  If too hot it comes out too easily and most of the molten plastic stays in the nozzle.  If too cold you can't get it out (although some have said you can twist the filament even at room temperature - I've not really tried that).